/// <summary>
/// Returns the <see cref="SchemaShape"/> of the schema which will be produced by the transformer.
/// Used for schema propagation and verification in a pipeline.
/// </summary>
public override SchemaShape GetOutputSchema(SchemaShape inputSchema)
{
Host.CheckValue(inputSchema, nameof(inputSchema));
if (!Transformer.IgnoreMissing && !ColumnSelectingTransformer.IsSchemaValid(inputSchema.Select(x => x.Name),
Transformer.SelectColumns,
out IEnumerable <string> invalidColumns))
{
throw Host.ExceptSchemaMismatch(nameof(inputSchema), "input", string.Join(",", invalidColumns));
}
var columns = inputSchema.Where(c => _selectPredicate(c.Name));
return(new SchemaShape(columns));
}